Re: [PATCH 5/5] scsi: Set allocation length to 255 for ATA Information VPD page

From: Nix
Date: Thu Apr 15 2021 - 09:25:13 EST


On 14 Apr 2021, Maciej W. Rozycki stated:

> Set the allocation length to 255 for the ATA Information VPD page
> requested in the WRITE SAME handler, so as not to limit information
> examined by `scsi_get_vpd_page' in the supported vital product data
> pages unnecessarily.
>
> Originally it was thought that Areca hardware may have issues with a
> valid allocation length supplied for a VPD inquiry, however older SCSI
> standard revisions[1] consider 255 the maximum length allowed and what

Aaaah. That explains a lot! (Not that I can remember what SCSI standard
rev that Areca firmware claimed to implement. I know I never updated the
firmware, so it's going to be something no newer than mid-2009 and
probably quite a bit older.)

> Nix,
>
> I can see you're still around. Would you therefore please be so kind
> as to verify this change with your Areca hardware if you still have it?

It's been up in the loft for years, but I'll get it out this weekend and
give it a spin :) this'll let me make sure the disks still spin as well,
which matters for an in-case-of-lightning-strike disaster-recovery
backup box.

(I just hope this kernel boots on it at all. It's about three years
since I retired it... let's see!)

> It looks to me like you were thinking in the right direction with:
> <https://lore.kernel.org/linux-scsi/87vc3nuipg.fsf@xxxxxxxxxxxxxxxx/>.

It's the sort of mistake I could see myself making: an easy mistake to
make when so many things in C require buffer size - 1 or you get a
disastrous security hole...

--
NULL && (void)